Sculpture apparatus for correcting curvature of the cornea
Patent 4911711 Issued on March 27, 1990. Estimated Expiration Date: 
March 27, 2007. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
March 27, 2007. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3348547 3703176 3705758 Laser material removal apparatus Method of treating object by laser beam and apparatus therefor Illuminating device for providing an illumination beam with adjustable distribution of intensity and a pattern-transfer system comprising such a device Reflective beam rotator Method and apparatus for optical beam shaping Optical system for synthesizing plural light beams Material working apparatus InventorsAssigneeApplicationNo. 938633 filed on 12/05/1986US Classes:606/5, Recurving or reshaping of the eye219/121.6, Using laser219/121.68, Etching or trimming219/121.75, With lens219/121.83, With monitoring606/11Beam energy control or monitoringExaminersPrimary: Cohen, Lee S.Assistant: Shay, David M. Attorney, Agent or FirmForeign Patent References
International ClassA61M 005/06ClaimsWhat is claimed is:1. Apparatus for performing an ablating sculpture of the anterior surface of the cornea of an eye, comprising an excimer laser for pulsed emission of ultraviolet radiation in a beam of rectangular section wherein intensity distribution is generally uniform in the longer-dimensional direction and is generally Gaussian about the center of its shorter-dimensional direction; and optical elements in a path of beam transmission to the eye, including means for centering the beam on the viewing axis of the eye and for shaping the beam to a circle wherein said generally Gaussian distribution is symmetrical about a diameter of the circle and wherein the diameter of the circle conforms to that of the area of the cornea to be subjected to ablation; said optical elements including beam-rotating means, whereby the orientation of the Gaussian distribution may be subjected to rotation with respect to the eye. 2. Apparatus according to claim 1, in which said beam-rotating means includes provision for selective rotational adjustment and setting of the orientation of the Gaussian distribution, whereby an astigmatism-correcting change of cornea curvature may be effected for a given laser-beam exposure to the eye. 3. Apparatus according to claim 1, in which said beam-rotating means includes provision for continuously driven rotation in the course of a given laser-beam exposure o the eye, whereby for beam rotation of at least 180 degrees at the eye and for the direction of a given laser-beam exposure to the eye, a myopia-reducing change of cornea curvature may be effected. 4. Apparatus according to claim 1, in which said beam-rotating means includes provision for beam rotation in the course of a given laser exposure to the eye, the rate of rotation being a function of angular orientation of the Gaussian distribution, such that more time is spent at the orientation identifiable with an astigmatism to be corrected, as compared with less time spent at the orientation perpendicular to the astigmatism axis. 5. In apparatus using an ultraviolet laser to correct an optically deficient eye by volumetric ablative removal of corneal tissue from the anterior surface and with penetration of the stroma, wherein laser-beam delivery is on an optical path which terminates with a fixed cornea-impingement axis aligned with the axis of the eye, and wherein beam-characterizing means so characterizes intensity distribution within a predetermined circle of laser-radiation exposure to the cornea as in the course of a predetermined exposure time to so distribute the cumulative depth of ablation as to achieve a new and improved corneal curvature, the improvement wherein the laser is an excimer laser and wherein beam-homogenizing means for effecting a relatively uniform cross-sectional distribution of flux density is on said path downstream from the laser and upstream with respect to the characterizing of intensity distribution, said beam-homogenizing means comprising scraper means limiting beam margins to a rectangular section (a) which is elongate in one dimension and which is of substantially uniform intensity profile along said one dimension and (b) which is relatively narrow in the other dimension and which is within a substantially 2:1 range of dimensional intensity-profile variation along said other dimension, and refractive anamorphic beam-expansion means oriented to expand said relatively narrow dimension to substantially the extent of said one dimension. 6. In apparatus using an ultraviolet laser to correct an optically deficient eye by volumetric ablative removal of corneal tissue from the anterior surface and with penetration of the stroma, wherein laser-beam delivery is on an optical path which terminates with a fixed cornea-impingement axis aligned with the axis of the eye, and wherein beam-characterizing means so characterizes intensity distribution within a predetermined circle of laser-radiation exposure to the cornea as in the course of a predetermined exposure time to so distribute the cumulative depth of ablation as to achieve a new and improved corneal curvature, the improvement in which the laser is an excimer laser producing an output beam of generally rectangular section wherein intensity distribution is generally uniform along an elongate first dimension and is characterized by generally Gaussian distribution along a second dimension transverse to said first dimension, beam-processing means including one or more optical elements on said path, said one or more optical elements being operative (a) substantially only along said second dimension of the beam section and (b) to expand said second dimension for substantial equality with said first dimension. 7. The improved apparatus of claim 6, in which said one or more elements includes refractive anamorphic beam-expansion means oriented to expand said second dimension to substantial equality with said first dimension. 8. The apparatus of claim 6, in which said beam-processing means includes scraper means limiting the beam to a circular section following beam-expansion. 9. The improved apparatus of claim 6, in which the height and width dimensions of the expanded beam are substantially greater than the beam-section dimensions at delivery to the eye, means for characterizing the flux distribution on the scale of said greater dimensions, and beam-condenser means operative to reduce the characterized beam to said predetermined circle. 10. The improved apparatus of claim 9, in which said beam-condenser means is a zoom telescope. 11. The improved apparatus of claim 6, in which a multiple-station turret mounts a plurality of different flux-distribution filters at each of a succession of stations that are individually and selectively indexible into said path following beam-expansion, and a beam-condenser downstream from said turret. 12. The improved apparatus of claim 6, in which an indexible turret is characterized by a successive plurality of openings at predetermined angular spacing, said openings being characterized by progressively changing beam-scraping radius about said path when each opening is indexed into position centered on said path. 13. The improvement of claim 6, in which said beam-processing means is contained in an enclosure having a beam-entry port proximal to beam exit from the laser and a beam-exit port proximal to the location of characterized beam delivery to the eye. 14. The improvement of claim 13, in which said enclosure is an environmentally sealed enclosure. 15. The improvement of claim 13, in which said enclosure has an environmental filling of a gas inert to laser radiation. 16. The improvement of claim 15, in which said gas is dry nitrogen. 17. The improved apparatus according to claim 6, in which the range of intensity-profile variation along the height dimension is in the range 2:1 or less. 18. In apparatus using an ultraviolet excimer laser to correct an optically deficient eye by volumetric ablative removal of corneal tissue from the anterior surface and with penetration of the stroma, wherein laser-beam delivery is on an optical path which terminates with a fixed cornea-impingement axis aligned with the axis of the eye, wherein beam-characterizing means so characterizes intensity distribution within a predetermined circle of laser-radiation exposure to the cornea as in the course of a predetermined exposure time to so distribute the cumulative depth of ablation to achieve a new and improved corneal curvature, and wherein beam-homogenizing means for effecting a relatively uniform cross-sectional distribution of flux density is interposed between the laser and said beam-characterizing means, the improvement in which computer means includes digitally stored tolerance data reflecting a predetermined level of uniformly distributed laser-beam intensity distribution across the beam prior to characterization of intensity distribution, and in which beam-monitoring means associated with said computer means includes a beam-sampling splitter positioned in said path prior to characterization of intensity distribution, said beam-monitoring means being electrically responsive to intensity distribution across the sampling beam and producing a digital output indicative of such distribution, said computer means indicating the beam-sampled distribution in relation to the digitally stored tolerance data. 19. The apparatus of claim 18, in which shutter means on said path and downstream from said splitter is normally closed to foreclose delivery of laser radiation to the eye, said shutter means having an actuating connection from said computer means and being actuable to open condition only in the event that the monitored distribution data conforms with the digitally stored tolerance data. 20. The improved apparatus of claim 18, in which said beam-processing means includes spatial-filter means following beam-expansion, for removing high spatial-frequency intensity variations from the beam. 21. In apparatus using an ultraviolet laser to correct an optically deficient eye by volumetric ablative removal of corneal tissue from the anterior surface and with penetration of the stroma, wherein laser-beam delivery is on an optical path which terminates with a fixed cornea-impingement axis aligned with the axis of the eye, and wherein flux distribution is so characterized within a predetermined circle of laser-radiation exposure to the cornea as in the course of a predetermined exposure time to so vary with time the intensity distribution across the beam so as to distribute the cumulative depth of ablation and thereby achieve a new and improved corneal curvature, the improvement in which computer means include a digital storage of a time-varying intensity distribution function across the beam that is predetermined to effect a selected curvature correction, and in which beam-monitoring means associated with said computer means includes a beam-sampling splitter positioned in said optical path after characterization of intensity distribution, said beam-monitoring means being electrically responsive to the time-varying intensity distribution in the sampling beam and producing a digital output that is indicative of the sampled distribution, said computer means indicating the beam-sampled distribution in relation to the digitally stored distribution data. 22. The improved apparatus of claim 21, in which the shutter means on said path and in downstream proximity to said splitter is normally closed to foreclose delivery of laser radiation to the eye, said shutter means having an actuating connection from said monitoring means and being actuable to open condition only in the event that the monitored distribution data and the digitally stored distribution data conform within predetermined tolerance limits. 23. The improved apparatus of claim 21, in which said beam-monitoring means includes a second beam-sampling splitter positioned in said path prior to time-varying characterization of the intensity distribution function, whereby homogeneity of the beam may be monitored prior to beam-characterizing. 24. The apparatus of claim 21, in which the characterizing of intensity distribution is a time-varying function of radius about the cornea-impingement axis. 25. The apparatus of claim 21, in which the characterizing of intensity distribution is a symmetrical function on laterally opposed sides of a diametrically extending axis intersecting the cornea-impingement axis, and selectively operable beam-rotation means for setting an angular orientation of the characterized beam consistent with the axis of an astigmatism to be reduced. 26. The apparatus of claim 25, in which said beam-rotating means is upstream with respect to said beam-sampling splitter. Other References
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